Portable winch

ABSTRACT

A portable winch and method of use is shown. One advantage of winches shown includes an ability to lower a boom or boom sections into limited access exit pit for winching operations such as pipe bursting. Sectional boom designs shown provide the ability to easily raise and lower a boom large distances without the need for a single long boom. Selected winch designs shown include flexible inserts between the boom and the winch frame that help resist damage from unforeseen shifting of the device during operation. Designs and methods shown also include multiple pulleys on a boom end unit. Fasteners are shown that reduce build up of debris.

PRIORITY APPLICATIONS

This patent application is a Divisional of U.S. application Ser. No.11/747,386, filed on May 11, 2007, which claims the benefit of priority,under 35 U.S.C. Section 119(e), to U.S. Provisional Patent ApplicationSer. No. 60/747,590, filed on May 18, 2006, and U.S. Provisional PatentApplication Ser. No. 60/823,458, filed on Aug. 24, 2006, all of whichare incorporated herein by reference in their entirety.

TECHNICAL FIELD

This invention relates to devices and methods for pulling a flexibleline. Specifically, this invention relates to cable pulling devices,methods, and accessories for pipe replacement.

BACKGROUND

Winches with booms can be used for a number of applications. Forexample, in a pipe bursting operation, one method uses a cable, or wirerope to pull a pipe burster through a section of pipe to be replaced. Awinch with a boom can be used in a manhole or other small hole to pullthe cable and burst the pipe. Typically in such an operation, a newreplacement pipe is pulled along behind the pipe burster to replace theold pipe. An advantage of this method of pipe bursting includeseliminating the need to dig up the old pipe using a trench. Anotheradvantage of this method of pipe bursting includes the ability toreplace the old pipe with a new pipe that is substantially the samediameter as the old pipe. Fragments or portions of the old pipe aremerely pushed into the surrounding soil to make room for the replacementpipe.

One challenge with winches and pipe bursting includes the small spacesusually associated with the pulling end of the operation. For example,in a manhole, it may be difficult to assemble a boom for the winch, andto adjust the length of the boom. Further, during a winching operation,booms may shift due to partial collapse of the wall of the hole or otherreasons. What is needed is an improved winch and boom system thatprovides ease of setup, and other improved design features that providea robust device at an economical cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A shows an isometric view of a portable winch in a storageposition according to an embodiment of the invention.

FIG. 1B shows an isometric view of a portable winch in an operationalposition according to an embodiment of the invention.

FIG. 1C shows a close up view of a portion of a portable winch from FIG.1B according to an embodiment of the invention.

FIG. 2 shows a side view of a portable winch in pipe bursting operationaccording to an embodiment of the invention.

FIG. 3 shows an isometric view of a boom section according to anembodiment of the invention.

FIG. 4 shows a cross section view of a portion of a boom systemaccording to an embodiment of the invention.

FIG. 5A shows an isometric view of a boom section joint according to anembodiment of the invention.

FIG. 5B shows an isometric view of a boom section joint componentaccording to an embodiment of the invention.

FIG. 5C shows an isometric view of a mating boom section joint componentaccording to an embodiment of the invention.

FIG. 6 shows an isometric view of a portion of a portable winchaccording to an embodiment of the invention.

FIG. 7 shows an isometric view of a boom end portion of a portable winchaccording to an embodiment of the invention.

FIG. 8 shows an isometric view of another boom end portion of a portablewinch according to an embodiment of the invention.

FIG. 9 shows a side view of a deployed boom according to an embodimentof the invention.

FIG. 10 shows a side view of a boom in an intermediate state accordingto an embodiment of the invention.

FIG. 11 shows a close up isometric view of a boom component according toan embodiment of the invention.

FIG. 12 shows a flow diagram of a method of pipe bursting according toan embodiment of the invention.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown,by way of illustration, specific embodiments in which the invention maybe practiced. In the drawings, like numerals describe substantiallysimilar components throughout the several views. In the followingdescription, the term cable is defined to include metal cables, wirerope, or other lengths of flexible line of suitable strength to pulldevices as described below through a section of pipe. These embodimentsare described in sufficient detail to enable those skilled in the art topractice the invention. Other embodiments may be utilized andstructural, or logical changes, etc. may be made without departing fromthe scope of the present invention.

FIG. 1A shows a portable winch 100 including a frame 110 and a boomassembly 120. In one embodiment, a drum 114 is included to hold anamount of flexible line such as wire rope, cable, etc. that the portablewinch is designed to pull. In one embodiment, the drum 114 is a separatecomponent from a winch. In the embodiment shown in FIG. 1A, a winch 112is shown attached to the frame 110 adjacent to the boom assembly 120. Inone embodiment, the winch includes a dual capstan winch. Other winchdesigns such as single drum winches, etc. are also within the scope ofthe invention. In one embodiment, the winch 112 is driven by hydraulicmotors.

The boom assembly 120 as shown includes a boom section 122 and a boomend unit 124. In one embodiment, the boom assembly 120 includes ahousing 130 with a boom driver and other devices that are explained inmore detail below. In one embodiment, the housing 130 moves through useof a movable connection system 126. One embodiment shown in FIGS. 1A and1B illustrates the movable connection system 126 as a combination ofpivots and linkages driven by an actuator such as a hydraulic cylinder.Other embodiments include tracks and driving systems such as a toothedrack and a drive gear, etc. One advantage of linkage and pivotembodiments includes reduced manufacturing cost. In one embodiment, theboom end unit 124 includes a pulley as shown in FIG. 1A. Other devicesfor redirecting a flexible line are also within the scope of theinvention, such as skid plates, tubes, rollers, etc.

The boom assembly 120 of FIG. 1A is shown in a storage position suitablefor transportation of the portable winch 100. FIG. 1B shows the portablewinch 100 of FIG. 1A with the boom assembly 120 in an operationposition. The boom section 122 is oriented substantially vertically withrespect to a ground surface with the boom section 122 extended and theboom end unit 124 located at an operational distance below ground level.In one embodiment, at least one support strut 132 is included adjacentto the boom end unit 124 as shown in FIG. 1B. One or more support struts132 are used to hold the pulley of the boom end unit 124 away from awall of a pit during a winching operation.

In one embodiment, the boom assembly 120 is flexibly connected to theframe 110 within a given range of motion. In a winching operation, it ispossible to encounter shifts in the boom. Such shifts may be caused bypartial collapse of a wall that a support strut 132 is placed against.Having the boom assembly 120 flexibly connected to the frame 110provides a safety margin in the event that a boom shift occurs caused bya wall collapse or other reason. If the boom assembly 120 were solidlyfixed to the frame 110, the boom may become bent or damaged due to sucha shift. FIG. 1C show one embodiment of a flexible connection betweenthe boom assembly 120 and the frame 110. In FIG. 1, the flexibleconnection is accomplished using one or more elastomeric inserts 127.The elastomeric inserts are bolted or otherwise fastened between acomponent of the winch assembly 120 and the frame 110.

An advantage of elastomeric inserts includes inexpensive manufacture,and a limited range of motion, making the boom assembly 120 somewhatrigid with respect to the frame 110, yet still remaining flexible enoughto prevent damage to the boom, etc. in the event of a boom shift. Otherflexible connections include, but are not limited to steel springconnections, compressed gas cylinder connections, etc. In oneembodiment, the elastomeric inserts 127 are located between the movableconnection system 126 and the frame. Other locations are alsoacceptable, provided the boom 122 is allowed a range of motion withrespect to the frame 110.

FIG. 2 shows an embodiment of a portable winch 200 similar toembodiments described above in one possible application, specifically atrenchless pipe bursting operation. The portable winch includes a frame210 with a boom assembly 220 attached to the frame 210. A first hole 250and a second hole 252 are illustrated. In one embodiment, the first andsecond holes 250, 252 include manholes. A first pipe 254 is shown thatis to be replaced in the pipe bursting operation. In one method ofoperation, a flexible line 240 such as a wire rope begins at a winch212, and travels across a first pulley 213, then back over a secondpulley 214, then down along a boom 221. By pulling over multiple pulleysin the configuration shown in FIG. 2 a tension generated in the flexibleline 240 tends to pull the boom assembly 220 down against the frame 210where the first pulley 213 is attached. In such a configuration, theframe 210 takes the force of a pulling operation, in contrast to theconnection system such as connection system 126 shown in embodimentsdescribed above. As a result the connection system does not need towithstand the full pulling force of the flexible line 240, and can bedesigned more economically. Although the configuration described aboveincludes such advantages, the invention is not so limited. Other pulleysystems and connection systems can be used within the scope of theinvention.

In one embodiment, the boom 221 includes multiple sections. As shown inFIG. 2, for example, an end unit 224 is coupled to a boom section 222 toform the boom 221. A coupling 226 is located between the end unit 224and the boom section 222. Details of coupling designs are discussed inmore detail below.

In one embodiment, the position of the second pulley 214 locates theflexible line 240 within a cross section of the boom 221. An advantageof location within a cross section of the boom 221 includes keeping boomforces in compression during a winching operation, thus reducing thepossibility of buckling the boom 221 or a boom section. The flexibleline 240 then continues over a third pulley 216, and is redirected intothe first pipe 254 from an end located in the first hole 250 to an endlocated at the second hole 252. A pipe bursting head 242 is then coupledto the distal end of the flexible line 240. In selected embodiments, apipe bursting head 242 includes an expander, pipe cutter, pipe breaker,etc.

The winch 212 then pulls the pipe bursting head 242 through the firstpipe 254 to burst or split the first pipe 254 into the surrounding soil.Fragments of bursted pipe 256 are shown in FIG. 2. In one embodiment, asecond pipe 244 is also attached to the pipe bursting head 242 and ispulled into place as the first pipe 254 is burst. Although pipe burstingis illustrated as one application of a portable winch, other operationsare also within the scope of the invention. Ductile pipe splitting, pipelining, or other pipe repair and replacement operations are also withinthe scope of the invention.

FIG. 3 shows a boom section 300 according to an embodiment of theinvention. In one embodiment, the boom section 300 is similar to boomsections discussed above. A boom body 310 is shown with a first end 312and a second end 314. In one embodiment, an engaging feature or features316 are included on a lateral side of the body 310. In one embodiment, anumber of spaced structures 318 are located on another lateral side ofthe body 310. In one embodiment, the spaced structures 318 are locatedon a side opposite the engaging feature or features 316.

In one embodiment, the engaging features 316 include a toothed rack toengage with a drive gear. In one embodiment, the engaging featuresinclude a frictional surface to engage a tire or a wheel, etc. In oneembodiment, the first end 312 is shaped to engage a second end 314 ofanother boom section similar to the boom section 300. In one embodiment,the first end 312 uniquely engages a second end 314 of another boomsection. In one embodiment, the first end 312 is adapted to engageeither a first end 312 or a second end 314 of another boom section. Inone embodiment, other sections such as an end unit 224 as describedabove include an end that is adapted to engage either a first end 312 ora second end 314 of a boom section 300.

FIG. 4 shows a close up view of a portion of a boom assembly 420 similarto embodiments described above. A first boom section 422 is shown with asecond boom section 424 ready to add to a total length of a boom. Anengaging feature 423 is shown located on an end of the first boomsection 422, and a mating feature 425 is shown located on an end of thesecond boom section 424. In the embodiment, shown, the engaging feature423 is designed to uniquely engage the mating feature 425. In oneembodiment, a slot configuration is used to form an initial alignmentbetween the engaging feature 423 and the mating feature 425 alongdirection 427. In one embodiment, a joint between the first section 422and the second section 424 is further secured using one or more boltsafter the engaging feature 423 and mating feature 425 have been joined.FIG. 4 also shows a third boom section 470 on a shelf 472. In oneembodiment, the shelf 472 includes engaging features to hold and alignone or more of the next boom sections and make adding boom sections tothe boom length easier. By holding multiple boom sections, the shelf 472increases the efficiency of extending or retracting a boom.

As shown in FIG. 4, in one embodiment, toothed racks are included inboth the first section 422 and the second section 424 that line up afterjoining the two sections. A boom driver 432 is shown within a housing430 that engages the boom sections. In the embodiment shown, the boomdriver 432 includes a drive gear that engages a lateral side of the boomsections using a toothed rack. As discussed above, other lateralengaging methods such as frictional engagement, etc. are also within thescope of the invention.

In one embodiment, the boom driver 432 is actuated using a hydraulicmotor or motors. In FIG. 4, a first gear 434 is coupled to at least onehydraulic motor to actuate the boom driver 432. Other actuators such aselectric motors, internal combustion driven gears, etc. are within thescope of the invention.

FIG. 4 further illustrates a linkage system 428 coupled to an actuator426 such as a hydraulic cylinder. In one embodiment, the housing 430moves between an operation position and a storage position as describedabove through use of the linkage system 428 and the actuator 426.Although a hydraulic cylinder actuator 426 and a linkage system 428 areshown, the invention is not so limited. One of ordinary skill in theart, having the benefit of the present disclosure will recognize thatalternative mechanisms can be used to move between an operation positionand a storage position. The configuration shown in FIG. 4, howeverincludes an advantage of being inexpensive to manufacture and simple tooperate.

A pulley 450 is also shown in FIG. 4, similar to pulleys described inembodiments above. In one embodiment, the flexible line that is beingpulled by the winch travels over the pulley 450 and is guided into achannel 429 of the boom section 422. Pulling forces are shown by arrow461 directed along a long axis of the boom section 422. Using theconfiguration shown in FIG. 4, a flexible line transmits pulling forcesto the boom in compression close to a central axis of the boom section422. In contrast, if the flexible line is guided along side the boomsection 422, the pulling forces increase the likelihood of buckling inthe boom section 422.

A boom lock device 460 is further shown in FIG. 4. In one embodiment,the boom lock 460 includes a sliding portion 462 with a slot 464 locatedon one side. FIG. 4 shows a lever 466 coupled to the sliding portion 462to actuate it back and forth for engagement or disengagement with theboom section 422. Although a lever 466 is shown, other actuating devicesare within the scope of the invention, such as knobs, solenoids,hydraulic or electric actuators, etc. In one embodiment, at least oneslot 464 or similar feature mates with one or more of a number of spacedstructures 421 similar to spaced structures 318 described above. In oneembodiment, the spaced structures include steel bars welded in placewithin a portion of the boom section 422. Although steel bars are shown,other spaced structures that are configured to engage one or more slots464 are also within the scope of the invention. Examples include, butare not limited to protrusions or recesses formed into a boom section,other mechanical engaging features, etc. Advantages of the slidingportion 462 and slot 464 shown in FIG. 4 include inexpensivemanufacture, and engagement of more than one spaced structures 421 atone time while actuated, giving higher strength than if only one spacedstructure 421 were engaged.

Other advantages of configurations with a boom lock 460 include theability to easily raise or lower a boom when the boom lock 460 isdisengaged. Then, by engaging the boom lock 460, the boom is easilysecured at a particular length, and pulling forces 461 are onlytransmitted to portions of the boom lock 460 in contrast to pullingforces 461 being transmitted to the boom driver 432 or other linkageswithin the housing 430.

FIGS. 5A-5C show various components and views of a joint assembly 500between boom sections according to one embodiment of the invention. InFIG. 5A the joint assembly 500 includes an engaging unit 520 and amating unit 510. In one embodiment, the mating unit 510 includes one ormore slots 512, and the engaging unit 520 includes one or more tabs 522that fit within the slots 512. In the embodiment shown, the tabs 522 ofthe engaging unit 520 slide laterally into the slots 512 of the matingunit 510.

A locating pocket 516 and corresponding locating protrusion 526 areshown in an assembled condition of the joint assembly 500. In oneembodiment, the locating protrusions 526 include a pair of hex headedbolts, and the locating pockets 516 are machined to fit closely with theheads of the pair of hex headed bolts. In one embodiment, the locatingpockets 516 and the locating protrusions 526 provide a reference forwhen the engaging unit 520 and mating unit 510 are in alignment.

As shown in FIG. 4, in one embodiment, boom sections are joined togetherlaterally along direction 427 by sliding together a joint assembly suchas joint assembly 500. In embodiments that utilize locating pockets 516and locating protrusions 526, the boom sections are slid together untilthe protrusions 526 are stopped by the pockets 516. One advantage ofthis design includes the ability to assemble heavy boom sections withoutexcessive attention to alignment of the joint assembly. In oneembodiment, alignment of the joint assembly 500 also provides alignmentbetween holes 514 and depressions 524 as described below.

FIG. 5B shows the mating unit 510 from FIG. 5A. A pair of threaded holes514 are shown formed in the mating unit 510. FIG. 5C shows the engagingunit 520 from FIG. 5A. A pair of depressions 524 are shown formed in theengaging unit 520. The holes 514 in FIG. 5B pass through the thicknessof the mating unit 510, while the depressions 524 only partially passinto a surface of the engaging unit 520. This can also be seen in dashedlines shown in FIG. 5A.

In one embodiment, once the engaging unit 520 and mating unit 510 are inalignment, a bolt or other fastening member is secured between theengaging unit 520 and the mating unit 510 to further prevent anyunwanted separation of the joint assembly 500. In the embodiment shownin FIGS. 5A-5C, a pair of bolts (not shown) are threaded through theholes 514 of the mating unit 510, and ends of the bolts are seatedwithin the depressions 524 of the engaging unit 520. When the bolts aretightened, they both secure the joint assembly 500 between the holes 514and the depressions 524, and they force the mating unit 510 to tightenagainst the engaging unit 520, thus reducing any unwanted motion betweenboom sections, and increasing an amount of surface area contact withinthe joint assembly 500. In the embodiment shown, tightening bolts orother threaded members within the holes 514 and against the depressions524 forces the engaging unit 520 and the mating unit 510 apart along aboom axis, yet the units 510, 520 are still held captive by the tabs 522and slots 512 shown. As a result, the tabs 522 are pressed against theslots 512 to ensure solid contact within the joint assembly 500.

FIG. 6 shows a close up view of an assembly operation of a pair of boomsections. A first boom section 602 is shown already in place within aboom, while a second boom section 604 is shown ready for joining withthe first boom section 602 to add length to the boom. Similar toembodiments described above, an engaging feature 623 is shown located onan end of the first boom section 602, and a mating feature 625 is shownlocated on an end of the second boom section 604. In one embodiment, themating feature 625 includes one or more slots 612, and the engagingfeature 623 includes one or more tabs 622 that fit within the slots 612.

In one embodiment, a shelf 610 is attached to the boom assembly, to aidin alignment and attachment of the joint between the first boom section602 and the second boom section 604. In one embodiment, one or moreshelf tabs 620 are attached to the shelf 610 in a configuration thatsubstantially matches the tabs 622 on adjacent boom sections. In onemethod of operation, the second boom section 604 is first mated with theshelf tabs 620 using the slots 612 of the mating feature 625. Thispositions the second boom section 604 to be ready for joining to thefirst boom section 602 when the engaging feature 623 of the first boomsection 602 is at the right height. When the mating feature 625 and theengaging feature 623 are aligned, the second boom section 604 is slidinto place along direction 627.

As described in discussion of FIGS. 5A-5C, in one embodiment, a bolt orother fastener is then threaded or otherwise inserted into hole 614 andseated against depression 615. The bolt or other fastener (not shown)can serve a number of functions. In one embodiment the insertion in tohole 614 and into depression 615 further secures the joint between thefirst boom section 602 and the second boom section 604. In oneembodiment, the insertion in to hole 614 and into depression 615provides an aligning function to ensure that the first boom section 602and the second boom section 604 are centered over each other. In oneembodiment, the insertion in to hole 614 and into depression 615 pressesportions of the engaging feature 623 against portions of the matingfeature 625 to increase an amount of surface area in contact at thejoint. High surface area contact is desirable because it increases thestiffness of the joints within a multiple section boom.

In one embodiment, a retaining feature 630 is included to keep thesecond boom section 604 in place on the shelf 610 before a boom sectionjoining operation. In one method, the retaining feature 630 is firstremoved in order to place the next boom section on the shelf tabs 620.The retaining feature 630 is then replaced to retain the boom section onthe shelf 610 until the boom section is secured onto the boom.

FIG. 7 shows a boom end portion 700 according to one embodiment. A boomsection 710 is included to attach to other boom sections as described inembodiments above. An end unit body 720 is shown coupled to the boomsection 710, with a pulley 722 to redirect a flexible line such as wirerope, etc. A first support strut 724 and a second support strut 728 areshown in FIG. 7. Although two support struts are shown, otherembodiments may include one or more than two support struts. A firstbumper 726 is shown coupled to the first support strut 724, and a secondbumper 730 is shown coupled to the second support strut 728. In oneembodiment, the addition of bumpers serves to reduce slippage of thesupport struts and/or to reduce damage to an adjacent surface such as amanhole.

A number of strut adjustments are shown in FIG. 7. In the example shown,both the first support strut 724 and the second support strut 728include multiple adjustment possibilities. For simplicity in discussion,only the adjustments to the first support strut 724 are detailed. Apitch adjustment 732 is shown, and a yaw adjustment 734 is shown. Anextension adjustment 736 is also included in the configuration of FIG.7. In one embodiment, a number of spring loaded pins are used incombination with a series of drilled holes to facilitate adjustments. Inoperation, to make an adjustment, a collar portion 731 is pulled to pullback a pin (not shown) from within one of the holes 733. When released,the pin and collar 731 are biased to normally seat the pin within one ofthe holes 731. An advantage of spring loaded pins, includes the securityand mechanical robustness of a pin in hole adjustment, combined withconvenience of a pin that will not get lost or dropped during anadjustment.

FIG. 8 shows another boom end portion 800. A boom section 810 isincluded to attach to other boom sections as described in embodimentsabove. An end unit body 820 is shown coupled to the boom section 810including component to redirect a flexible line such as wire rope, etc.A first pulley 824 and second pulley 824 are shown in FIG. 8. Similar toembodiments shown above, one or more support struts 830 are included,with bumpers 832 coupled to their distal ends. In one embodiment, anorientation and a length of the support struts are adjustable as shownin more detail below. One adjustment device includes a spring pinassembly 834 which is also discussed in more detail below. In oneembodiment, ball and socket joints are provided between an end of thestrut 830 and bumpers 832. Ball and socket joints improve forcedistribution to irregular wall surfaces during a pulling operation.

FIG. 9 shows a the boom end portion 800 connected to another boomsection 812. FIG. 9 shows the boom end portion 800 deployed in abursting operation within a manhole 900 as an example. The examplemanhole 900 includes a narrow top portion 902 and a larger diameterlower portion 904 where bursting typically takes place. A threadedportion 836 is shown extending from the strut 830 to brace against thewall of the manhole 900. One embodiment includes the threaded portion836 for length adjustment with respect to the strut 830. The embodimentshown in FIG. 9 includes a corresponding threaded adjuster 838 with ahandle to quickly adjust the length of the threaded portion exposed froman end of the strut 830. In selected embodiments, as shown in FIG. 9, aspring pin assembly 834 is further included for rough length adjustment.The combination of the spring pin assembly 834 adjustment with thethreaded portion 836 adjustment provides fast adjustability over bothcoarse ranges of motion and fine tuning using the threaded member 836.

The bumper 832 is shown in contact with the wall of the manhole. In oneembodiment, the bumper 832 is coupled to the threaded portion 836 with aball and socket joint 831. An advantage of using a ball and socket jointincludes the ability to conform to difficult wall conditions within themanhole 900 that are sometimes encountered in bursting operations.

When only a single pulley boom end unit configuration is used there is alimit on horizontal space within the manhole 900. As shown in FIG. 9,there is only a given amount of space 825 between the wall of themanhole 904 and the edge of the first pulley 822. When a burster 850 ispulled into the manhole 900, a length 856 of the burster 850 determineshow easily the burster 850 can be removed from the attached new pipe 856to finish the bursting and new pipe installation.

In a single pulley boom end configuration, it is easiest to remove theburster 850 if the burster length 856 is shorter than the space 825. Inmany situations, the space 825 is not large enough, or the space 825leaves little room to maneuver. If the burster 850 is pulled tight upagainst the pulley, the boom end portion, or the burster can be damaged.

According to an embodiment of the invention, a second pulley 824 isincluded as shown in FIG. 9. One advantage of using a second pulley 824is the ability to offset the first pulley 822 and the second pulley 824by a distance 826. The extra distance 826 is then available to betterallow the burster 850 to fully enter the manhole 900. The extra distance826 also provides an additional margin of room to avoid damage to theboom end unit 800 or the burster 850 resulting from pulling the burster850 too close.

In one embodiment, a rotating joint 821 is included to allow relativemotion between the first pulley 822 and the second pulley 824. Asecuring feature 828 is included to inhibit relative motion between thepulleys 822, 824 during a bursting operation. In one embodiment as shownin FIG. 9, the securing feature includes a bolt passing through a holeto inhibit relative rotation between the pulleys, although the inventionis not so limited. Other securing features may include a ratchet, springpin, latch, etc. A feature provided by the rotating joint 821 is furtherillustrated in FIG. 10.

The boom end unit shown in FIG. 10 illustrates one configuration to beused for inserting or removing the boom end unit 800. As illustrated,frequently an entry diameter such as 902 is smaller that a diameter at alocation 904 where the boom end unit will operate. In one embodiment,the boom end unit 800 is changeable between a bursting operationconfiguration, and an insertion or removal configuration. One example ofan insertion or removal configuration is shown in FIG. 10. A boom endunit cross section dimension 802 is shown to illustrate an increasedability to insert or remove the boom end unit through narrow openingswhen in the configuration shown. In one example, the second pulley 824rotates with respect to the first pulley 822. The configuration shown inFIG. 10 additionally shows the strut 830 rotating with respect to thefirst pulley 822. In one embodiment, spring pins or other fasteners holdcomponents of the boom end unit in a configuration for insertion orremoval. In one embodiment, selected component such as the second pulley824 are not locked. For example the second pulley 824 can rotate freelywith respect to the first pulley 822 about the joint 821 in oneconfiguration.

FIG. 11 shows a close up view of one type of fastener for use withembodiments of the invention as described in the present disclosure. Onetype of fastener discussed in configurations above includes a spring pin1100. The spring pin 1100 shown in FIG. 11 includes a fixed portion 1110with a pin 1112 that is movable with respect to the fixed portion 1110.A “T” handle 1116 is shown in the example, coupled to the pin 1112. Aspring 1114 is included to bias the pin 1112 to a normally down positionwithin at least one hole 1130. A slot 1118 is included in the example ofFIG. 11 that substantially matches the handle 1116 to provide a downposition of the pin 1112 when the handle 1116 is within the slot 1118.

In one method of operation, the pin 1112 is pulled up against springtension, and rotated to sit outside the slot 1118 as shown in FIG. 11,when it is desired to unlock the joint. With the handle 116 resting ontop of the fixed portion 1110, outside the slot 1118, the pin is notengaged with any holes 1130, and the joint can be maneuvered with bothhands.

To engage the fastener 1100, the handle 1116 is rotated to line up withthe slot 1118, and the spring 1114 biases the pin 1112 down intoengagement with a hole 1130. Adjustment of the joint is easier with thisconfiguration, because the user does not have to hold the pin againstthe biasing spring 1114 while adjusting is being done, while at the sametime a simple twist of the handle 1116 returns the biases pin 1112 intoengagement.

In one embodiment, one or more openings 1120 are cut into a side of thefixed portion 1110. This configuration allows dirt or other debris oftenfound on job sites to move out of the fixed portion 1110, and clear ofthe pin 1112 and hole 1130 during a joint adjustment. This configurationprovides one level of improvement over closed designs that may jam dueto the presence of dirt, etc.

FIG. 12 shows one possible method of operation of a winch according toone embodiment. A boom driver is actuated against a lateral surface of aboom section to lower the boom section into a hole such as an exit pit.A pulley located at a distal end of the boom section is positioned neara pipe to be replaced, an end of which is exposed within the exit pit. Aflexible line such as a wire rope is then fed through the pipe to bereplaced and into an entry pit. A pipe burster such as a pipe expander,a ductile material cutter, etc. is then secured to the wire rope in theentry pit. A new pipe such as flexible polyethylene pipe is then securedto a back end of the pipe burster. When the winch is operated, the pipeburster is pulled through the old pipe, bursting it as it is pulled. Thenew pipe is pulled into place as the burster advances through the soil.

Embodiments of portable winches and methods of use as described abovehave a number of advantages. One advantage includes an ability to lowera boom or boom sections into limited access exit pit for winchingoperations such as pipe bursting. Particular boom sectional designsprovided in embodiments described above provide the ability to easilyraise and lower a boom large distances without the need for a singlelong boom. A sectional boom design allows for easy replacement of only asingle section if one happened to be damaged. A boom driver that drivesthe boom through mechanical or frictional interaction in both an upwardand a downward direction is useful in contrast to a gravity loweredconfiguration. A gravity lowered configuration may have problemslowering in some situations due to fouling of the boom with dirt.Selected embodiments further include flexible inserts between the boomand the winch frame that help resist damage from unforeseen shifting ofthe device during operation.

While a number of advantages of embodiments of the invention aredescribed, the above lists are not intended to be exhaustive. Althoughspecific embodiments have been illustrated and described herein, it willbe appreciated by those of ordinary skill in the art that anyarrangement which is calculated to achieve the same purpose may besubstituted for the specific embodiment shown. This application isintended to cover any adaptations or variations of the presentinvention. It is to be understood that the above description is intendedto be illustrative, and not restrictive. Combinations of the aboveembodiments, and other embodiments will be apparent to those of skill inthe art upon reviewing the above description. The scope of the inventionincludes any other applications in which the above structures andmethods are used. The scope of the invention should be determined withreference to the appended claims, along with the full scope ofequivalents to which such claims are entitled.

1. A boom pulley assembly, comprising: at least two pulleys mounted to aboom end unit, including: a first pulley with a tangent substantially inline with a boom; and a second pulley spaced laterally apart from thefirst pulley in a direction opposite from a distal end of a cable to bepulled.
 2. The boom pulley assembly of claim 1, further including ajoint between the first pulley and the second pulley, wherein a relativeposition of the first pulley with respect to the second pulley isselectable within a range of motion.
 3. The boom pulley assembly ofclaim 1, further including at least one strut coupled to the boom endunit, the strut having a length adjustment.
 4. The boom pulley assemblyof claim 3, wherein the length adjustment includes a threaded member. 5.The boom pulley assembly of claim 4, wherein the length adjustmentfurther includes a pin and hole length adjustment.
 6. The boom pulleyassembly of claim 5, further including a bumper with a ball and socketjoint between a distal end of the strut and the bumper.
 7. The boompulley assembly of claim 1, further including at least one fastenerincluding a spring pin, wherein the fastener includes an opening topermit flushing of debris from within the fastener.
 8. The boom pulleyassembly of claim 7, wherein the spring pin is normally biased with thepin engaged in a hole, wherein the fastener includes a hands freeselectable position with the pin disengaged from the hole.
 9. A portablewinch, comprising: a winch; a boom assembly, including: two or more boomsections; a boom driver that mechanically engages a lateral side of thetwo or more boom sections fixed in relation to one another to raise andlower the boom sections; a flexible line coupled to the winch; a boomend unit, including: a first pulley with a tangent substantially in linewith a boom; and a second pulley spaced laterally apart from the firstpulley in a direction opposite from a distal end of a cable to bepulled.
 10. The portable winch of claim 9, wherein the two or more boomsections include substantially the same cross section dimensions, andare coupled end to end.
 11. The portable winch of claim 9, wherein thesecond pulley is adapted to be positioned in both a first positionspaced laterally apart from the first pulley and a second positionsubstantially in line with the boom assembly.
 12. The portable winch ofclaim 11, further including a rotary joint between the first pulley andthe second pulley that permits movement between the first position andthe second position.
 13. The portable winch of claim 9, wherein the boomdriver laterally engages a toothed rack on a lateral side of the two ormore boom sections.
 14. The portable winch of claim 9, further includinga locking mechanism to physically lock the two or more boom sections ata selected depth within a hole.
 15. A boom pulley assembly, comprising:a pulley adapted to mount to an end of a boom assembly; one or moresupports moveably coupled to the pulley at a joint; a plurality of holesto select a position of the joint; and a spring pin assembly to engageone of the holes, including: an optional engaged position of the pin,wherein the engaged position is normally biased by a spring into one ofthe holes; an optional disengaged position of the pin, where the pin isheld out of the holes, against the bias of the spring in a hands freeconfiguration.
 16. The boom pulley assembly of claim 15, furtherincluding one or more opening to permit flushing of debris from withinthe spring pin assembly.
 17. The boom pulley assembly of claim 15,wherein the joint includes a rotating joint.
 18. The boom pulleyassembly of claim 15, wherein the joint includes a linear extensionjoint.